docs: def validate_source(ident, comment=None):
      '''Validate a source for automatic harvesting'''
      source = get_source(ident)
      source.validation.on = datetime.now()
      source.validation.comment = comment
      source.validation.state = VALIDATION_ACCEPTED
      if current_user.is_authenticated:
          source.validation.by = current_user._get_current_object()
      source.save()
      schedule(ident, cron=current_app.config['HARVEST_DEFAULT_SCHEDULE'])
      launch(ident)
      return source